badbob94

just bought a 92 T4R for my daughter. Got a good price, $1500. Clean, no rust, body and interior in good shape. 3VZE, auto, 4x4, AC, power steering. This is my 4th T4R.

It has an engine knock! Not the ticking injector but a true knock. I've read through old threads and got a sense of the possible issues: sticky valve, bad camshaft, crankshaft, main bearing. Bad rod, lifter, rocker, and so on.

I'm starting a thread to get help diagnosing the problem by figuring out what steps to take. Can you give me a hand?

Here is what I know/done so far:

1) check engine light is NOT on
2) 173k miles
3) knock is worse when cold, gets much quieter as the engine warms up (a good 15 minutes.
4) oil pressure gauge normal
5) heat gauge normal
6) done-put Seafoam in fuel --helping to run soother and more power
7) put Seafoam in oil--helped quite the knock but has not gone away
8) knock is present at all RPMs--but quiets when deaccelerating like going down a hill and letting off the gas.
9) resent oil change--oil looks clean.
10) did notice cracked vacume hose going to the PS pump.

I got a stethoscope so I'll try to pinpoint the knock location and post my findings

What should I test next?

Compression? Remove sparkplug wires one at a time to see if the knock goes away? Remove belts to see if the knock is from AC compressor, etc.

Thanks in advance for the help.

Badbob

badbob94

Ok, we spent the day working on the car.

Did a more thorough visual inspection. Found two rotted vacuum hoses. 1) small hose leaving charcoal canister; 2) medium hose entering the PS pump.

I found a small amount of oil and coolant leaking between the tranny and rear motor. I'm not sure where the coolant is coming from, that is more of a concern for me--any ideas? Heater coil hose, perhaps?

PS pump has a few minor leaks.

We put 1/2 pint in of SeaFoam in the vacuum system. Seems to run smoother but we still have the knock.

Went around the engine with stethoscope. I could not detect any different sounds. However, I was idling it in the garage. When we put it in drive the knock is more pronounce.

Key--the knock gets quieter the more I drive it.

Then we disconnected each spark plug wire and found the knock went away when we disconnected cylinder #2!

We then ran a compression test. Here are the results:

#1=140psi
#2=120psi
#3=135psi
#4=130psi
#5=130psi
#6=130psi

Do you think #2 is low because of a valve problem?

What do you think the next step should be?

Thanks,

Badbob

MudHippy

Throw in the towel. Quit while you're ahead.

Those compression numbers only tell me one thing. It's definitely rebuild time.

So, yeah. Plan on replacing pretty much everything. And then you might be a little surprised, when it only needs almost everything replaced to meet OEM specs. Which will seem a little better in comparison. And you won't feel as unlucky for buying a big sour ol' lemon like ya did.

Have fun!

TNRabbit

Those compression numbers are REALLY low for the 3vze.

The coolant down the rear is PROBABLY coming from the upside-down u-shaped hose under the rear of the intake manifold (passenger side). Do yourself a favor and REMOVE THE HOOD to check it out-- 4 bolts & 5 minutes later, you'll be much happier. More light & TONS easier to get at. LONG needlenose will allow you to remove it if necessary without removing the entire intake.

badbob94

Thanks for the reply and the tip. I'll take a look at the hose.

I know the compression is low. Manual specs a min of 142psi. The vehicle is just for my daughter to get back and forth to school. The price is right and she is learning how to work on cars.

As for #2 valve I'm thinking I'll need to pull the head off and take a look. I guess on the good side it could just need an adjustment, worse case would be we need to rebuild the head.

Thanks again,

Badbob

MudHippy

I can tell you what you'll probably find when you do pull the heads, with regards to the valves. The exhaust valves and seats are going to look like crapola. And will need either ground or replaced. Adjustment will be required afterwards. The intake valves will likely be in good enough shape to reuse. And will probably not even need adjustment.

However...

I'm pretty sure what else you'll probably find with regards to the pistons and cylinders. MAJOR scoring and/or gouging on the cylinder walls. And if you were to remove the pistons, you would find them heavily scored/gouged, possibly cracked, and with rings that are COMPLETELY shot. It's these things that are causing the massive loss of compression on all cylinders(and possibly the knocking sound in one of them, ever heard of piston slap?). Not the valves.

So, you can do what you want with the heads. That's not going to really solve much, if anything. And I highly doubt it will make ANY difference with the "knock". Whereas, doing a proper rebuild likely would.

Good luck!

Team420

X2!! A knock is usually a sign of lower end issues, valve usually tick... Sounds like a full rebuild is in order.

badbob94

Mudhip, you're bumming me out. I hope its not the bad. One thing I forgot to mention is that I'm at 7000'.

The factory min for compression for the 3vze is 142psi. using an altitude adjustment factor of .8106, the min compression at 7000' is 115psi.

My vehicle is within specs. it drives find, has plenty of power, given its limitations, but just has a knock in #2. I suspect its just like you said, a burnt valve.

But I won't know until I pull the head. Either way the head needs to come off.

Would you rebuld yourself or buy a rebuild motor with a warranty? i see some for around $1300, including the heads, with a 12mo warranty.

Badbob

lonewolve

Ihad a knock two days before i was to go on vacation with my 1995Toyota 4RUNNER SR5 3.0 , It sucked.Had to rent a vehicle to go on vacation Friggin Jeep Commander, I missed my 4RUnner so bad it hurt.
Anyhow when i got back it took me approximately 3 months an fove engines from s TOYOTA only junkyard to fins an engine that would run.I still had to do a head job after i got it back.
It runs great, but to be honest im paranoid ill be back to the drawing board. always wondering when ill be left with a great vehicle with a lousy engine.The 3.0 is probably Toyota's worst engineering mishap.I have a 2003 with a 4.0 way better engine great power sips gas for being an v-6 with a bigger body but it isnt like my 1995 which i love the way it drives an looks.
If i could give any advice , a reman engine isnt a bad option , maybe do the dual exaust thing to prevent the heads from overheating or having trouble with headgasket issues.thats my 2 cents.
its yer coin just make sure it will be worth it.
Tight Wraps & Tight Lines
Rick Wallace

MudHippy

I've already fully rebuilt my 3VZ-E, with no regrets.
Even if it were, which I don't believe it is, it's not anywhere near as bad an engine as popular opinion/internet myth/all the hype makes it out to be. IMO, it's a great engine for its era, with a less than ideal exhuast system. Other than that, it's one tough cookie.

imbatman19

Piston slap. Caused by too much clearance between piston and cylinder wall. Piston rings still expand enough to maintain compression but the piston has a slight wobble on power stroke down causing the piston skirt to "slap" the cylinder wall. This is why you don't hear it as much at idle and just after warm up when the piston has warmed before the block. Sometimes this is caused by overheating the engine at some point. Which is likely with a previous head gasket failure prior to recall repairs. The fix: rebuild the motor. Possibility of it never causing any problems except the annoying tick you are focused on: good. Chances you can get over it, ignore it, live with a little tick similar to a single cylinder diesel: mmmmmm maybe.

badbob94

Ok, thanks for the heads up about this. this could be the problem. When I pull the head this weekend, how can I test/diagnosis/measure to see if this is the problem?

Thanks,
Badbob

badbob94

Mudhip--I'm reading a lot about the exhaust problem. do you recommend a fix? Is it the exhaust manifold? or something past the catconverter? Will and aftermarket exhaust solve the problem?

Badbob

imbatman19

After the head is off, turn the motor till the piston is at the very bottom. You might be able to see scoring on the sides of the cylinder wall. With the piston at the top use a feeler gauge to check clearance between piston and cylinder is below tolerance. If it's really bad you might even be able to rock the piston on its pin. If the cylinder is larger at the bottom than it is at the top you might not be able to tell anything from the top. Then you need to move to the bottom for measurements.

Team420

Notice in your second post the results for cyl 2, I'n my experience... its more important that all cyl are close to the same #, than how high that # is... Even Toyota says, 142 psi min, but... No more than 17 psi difference between any cyl, so your #'s are not within spec. Either way, you have a knock, and will be pulling the heads, just be sure to closely and carefully inspect the pistons, rings, and cyl walls.

May want to run a leakdown test, as well as a cooling system pressure test to get an idea of where exactly your loosing compression, but IMHO, usually when you pull a plug wire and the knock goes away, its a sign of piston slap, or a bad bearing, the knock goes away because there is no cumbustion.

imbatman19

It's the crossover. Go with headers and dual out to the rear.

jbtvt

Great posts all around! What sort of noob are you?

imbatman19

I like wine and cheese by the fire, quiet walks on the beach, dinner by candle light, and snuggling under a thick blanket on cold winter nights. Just a 4runner lover since the beginning.

badbob94

this afternoon we pulled off the intake manifold and valve covers and measured the valve clearance. Everything spec out. 2-3 valves where .001" over but nothing glaring out of place.

So, next step, as we bore down into this diagnosis is to pull the head and have look.

All in all, everything looks clean. inside the valve covers is was pretty dark brown, but no built up sludge.

We broke 3 of the 6 injector wire connectors--ARRG! So brittle, they just snapped. One more thing to fix.

Badbob

MudHippy

I would think it's the crossover's location primarily. Replacing the exhaust manifolds with headers and relocating or removing the crossover would probably be the best thing you could do. Simply relocating or removing the crossover and using the stock exhaust manifolds would probably be the next best thing you could do. Headers w/o relocating or removing the crossover would be next best after that. And improving the flow of the exhaust from the intake manifold/headers back, being next best after that(as in replacing with hi-flow, or removing the cat and muffler). If that makes any sense.

So, headers w/relocated or removed crossover and an open exhaust from there back(no cat, no muffler) would be ideal. IMO. I'm not recommending anything though. Other than you do whatever it is you want to/can afford to/are able to get away with(). And anything you can do to try and solve a problem is usually better than doing nothing at all...so...